Basic Commands

These are basic terminal commands that every Linux user must know. Most of the Linux administrators will tell you that that the Linux terminal is the most powerful tool for server management and other security stuff. Open your terminal on any Linux distribution and try out the list of commands given below. In case you don't have Linux installed kindly refer our article on how to install Linux on system or how to install it on Sun VirtualBox , to access Linux inside Windows itself. So, lets practice them one by one.

The commands are highlighted in bold letter.

"#" Indicates that you are a root user or super user

"$" Indicates that your power is limited

Now lets begin with

pwd

Command to view the present working directory

Syntax

[root@bOtskOOl root]#pwd

 

cd

to change the working/present directory

Syntax

[root@bOtskOOl root]#cd /home/student

where '/home/student' is the desired directory to be change from '/root'

 

ls -l

for listing the files as well as directories those are kept in the particular working directory

Syntax

[root@bOtskOOl root]#ls -l

 

ls -la

same as 'ls -l' but by this command we can also see the hidden files.

Syntax

[root@bOtskOOl root]#ls -la

 

ls -li

same as 'ls -la' but it will also shows us the inode number of

each and every file

Syntax

[root@bOtskOOl root]#ls -li

 

ls

by this command we can see only file name nothing else

Syntax

[root@bOtskOOl root]#ls

 

mkdir

to make a new directory

Syntax

[root@bOtskOOl root]#mkdir newdirname

 

rmdir

to remove a empty directory

Syntax

[root@bOtskOOl root]#rmdir directoryname

 

rm

 to remove a empty file

Syntax

[root@bOtskOOl root]#rm filename

rm [-i/-r/-f]

to remove a directory with its subdirectories as well as its

files that is to remove a directory which already contains some files in it

Syntax

[root@bOtskOOl root]#rm -i directory/filename

-i stands for interactively

-r stands for recursively

-f stands for forcefully

 

cp

 to copy something in a destination file or directory

Syntax

[root@bOtskOOl root]#cp sourcepath destinationpath

 

mv

to move one file or directory from one place to another place, it

is also used for renaming a directory or file

Syntax

[root@bOtskOOl root]#mv source destination

[root@bOtskOOl root]#mv oldfilename newfilename [to change the file name]

 

touch

to create a new empty file

Syntax

[root@bOtskOOl root]#touch

 

cat

to view the contents of a file and it is also used for creating a

new file with some contents

Syntax

[root@bOtskOOl root]#cat <file name> to view file contents

[root@bOtskOOl root]#cat > newfilename enter,then you can write something in

the file and then to save the file contents press ctrl+d then enter

 

clear

it will clear the screen(short cut ctrl+l)

Syntax

[root@bOtskOOl root]#clear

 

exit

to end a current session as well current terminal logging

Syntax

[root@bOtskOOl root]exit

 

man

 to view the manual page of commands for syntax and  usage

Syntax

[root@bOtskOOl root]#man commandname

 

info

to view the information about any command

Syntax

[root@bOtskOOl root]#mkdir info

 

--help

to view the help documents of a command

Syntax

[root@bOtskOOl root]#commandname --help

 

find location_to_search_in -name

to find any file or directory in linux file system

Syntax

[root@bOtskOOl root]#find / -name filename

 

su –

to become a super user

Syntax

[student@bOtskOOl student]$su -

output wil be

[root@bOtskOOl root#]

 

su username

to switch from one user to another users home directory

Syntax

[root@bOtskOOl root]#su student

output will be

[student@bOtskOOl root]#cd

[student@bOtskOOl student]#

 

su - username

to switch from one user to another user users home directory directly

Syntax

[root@bOtskOOl root]#su - student

 

useradd

to create a new user

Syntax

[root@bOtskOOl root]#useradd username

 

passwd

to give a password of a user

Syntax

[root@bOtskOOl root]#passwd nitesh

output will be

give a password for user nitesh:(here you have to type a password for nitesh user)

confirm password:(again type the same password)

 

userdel

to remove a user from linux

Syntax

[root@bOtskOOl root]#userdel nitesh

 

groupadd

to add a new group

Syntax

[root@bOtskOOl root]#groupadd groupname

 

groupdel

to delete a group

Syntax

[root@bOtskOOl root]#groupdel groupname

 

chown

to change the ownership of a file or directory

Syntax

[root@bOtskOOl root]#chown ownername filename

example:

[root@bOtskOOl /]#ls -l

output

drwxrw-rw- 2 root root 4096 Mar 11 12:03 abcd

(permission) (own) (group own)(size) (name)

[root@bOtskOOl root]#chown nitesh /abcd

in this example /abcd directory owner will be change to nitesh user

effect

[root@bOtskOOl /]#ls -l

drwxrw-rw- 2 nitesh root 4096 Mar 11 12:03 abcd

 

chgrp

to change the group ownership of a file or directory

Syntax

[root@nettec root]#chgrp newgroupownername filename

example

[root@bOtskOOl /]#ls -l

drwxrw-rw- 2 nitesh root 4096 Mar 11 12:03 abcd

[root@bOtskOOl root]#chgrp nitesh /abcd

effect

[root@bOtskOOl /]#ls -l

drwxrw-rw- 2 nitesh nitesh 4096 Mar 11 12:03 abcd

 

chmod

to change the permission of a file or directory

Syntax

[root@bOtskOOl root]#chmod value fileordirectoryname

example

[root@bOtskOOl /]#ls -l

drwxrw-rw- 2 nitesh root 4096 Mar 11 12:03 abcd

[root@bOtskOOl /]#chmod 402 /abcd

[root@bOtskOOl /]#ls –l

drw-----w- 2 nitesh nitesh 4096 Mar 11 12:03 abcd